This invention relates to methods and apparatus for generating heat and electrical energy from aluminum waste and other inexpensive aluminum products.
Approximately two megatons of aluminum is recently being lost in refuse annually within the United States. In spite of intensified efforts by major aluminum producers to recycle aluminum cans and other aluminum waste, the aluminum collected in the recycling drive has thus far totalled only about 0.1 megaton per year, i.e., only about 5% of the total aluminum lost. The rather low density of aluminum collection centers (only about 2,000 throughout the United States) appears to be the main reason for the very limited success of the recycling drive. Yet a much higher density of such collection centers is precluded by the cost of operating them and by the diminishing return per center with an increasing number of such centers.
It is an object of my invention to increase the collection and utilization of aluminum waste by providing a significant fraction of the population with an attractive use for various aluminum products.
The use of aluminum as anode material in batteries, especially aluminum-air batteries, has been taught in several of my publications and patents. However, these batteries utilize aluminum plates or sheets whose dimensions are prescribed by the particular battery design. It would be difficult to adapt the various forms of aluminum waste to the types of aluminum batteries disclosed in prior art.
In my copending application Ser. No. 813,483, filed July 7, 1977, I have disclosed the use of slurry-type aluminum anodes in conjunction with fluidized-bed air cathodes. Such slurry-type anodes should be capable of utilizing aluminum waste products after the latter had been cut up or otherwise comminuted into fine particles or chips suitable for being carried by an electrolyte into properly designed anode compartments. The particles of such a slurry-type anode represent one common form to which the various types of aluminum waste may be reduced in order to be suitable for electrochemical consumption yielding heat and electricity.
It is thus another object of my invention to provide the means whereby the various forms of aluminum waste reduced to a suitable size can be consumed electrochemically so as to yield heat and electrical energy.
The use of slurry-type anodes, as taught in my afore-cited copending application Ser. No. 813,483, may be associated with corrosion of the aluminum particles suspended in the slurry. This corrosion may be minimized by introducing corrosion-inhibiting additives into the electrolyte in which these particles are suspended.
However, it is yet another object of my invention to provide a more efficient and otherwise more practical means of generating electricity for such applications as electric vehicle propulsion, utilizing aluminum waste and other inexpensive aluminum products as an electrochemical fuel.
The aluminum-air batteries disclosed thus far necessitate frequent replacement of spent aluminum by fresh aluminum anodes, and, associated therewith, considerable work to ensure proper electrical connection of the fresh anodes to the negative battery terminals. In the slurry-type anodes disclosed in my aforecited copending application, the electrical connections between the suspended particles are inferior to those in packed-bed anodes.
It is therefore still another object of my invention to provide a convenient means of feeding aluminum fuel to an aluminum-air cell upon demand, and to provide improved electrical connections between said fuel and the negative cell terminal.
It is still another object of my invention to recover the aluminum hydroxide product generated in the electrochemical consumption of aluminum and thereby effect substantial savings in the energy and mineral resource content of the aluminum products presently lost in refuse.